1. Technical Field
This invention relates generally to methods and systems for transferring ions from one gas stream or other environment to another. More specifically, this invention comprises an ion transfer device arranged to urge ions contained in a first gas stream through an ion selective aperture into a second gas stream of different composition or characteristics.
2. Description of Related Art
Ions are routinely produced by subjecting a gas stream to an energetic source. Commonly used energetic sources include radioactive isotopes, plasmas, ultraviolet light, and many others. Such sources can produce ions in an environment (e.g., ambient air), that is not compatible with an ion destination (e.g., a detector, an ion trap, a reaction region, or a deposition or neutralization site). A solution to this problem is to transfer ions from one environment (e.g., a gas stream) to another, without transferring neutral components such as water or particles, which inhibit detection or interfere with performance at the ion destination.
Transferring ions from one gas stream to another may be necessitated by a variety of objectives, such as, but not limited to, the need to remove ions from a gas stream; to move ions that were created or collected in one gas stream to another gas stream that better meets the requirements of detection or identification equipment; to move ions to a gas stream to undergo chemical and/or physical reactions to enable differentiation among ions or to produce a specific product; to move ions from a gas of erratic or changing composition, such as ambient air, to a gas stream having a fixed and stable composition; and various combinations of the above. Ion transfer may be accomplished using a variety of known techniques including the use of ion selective apertures such as those described in U.S. Pat. Nos. 6,914,243, 6,949,740, and 7,060,976, and in pending U.S. Patent Application Publication No. 2008/0296493, all of which are incorporated herein by reference in their entirety. Ion focusing at atmospheric pressure is described in U.S. Pat. Nos. 6,818,889, 6,878,930, 6,949,740, and 7,087,898, which are incorporated by reference in their entirety.